cellar (n.)

early 13c., "store room," from Anglo-French celer, Old French celier "cellar, underground passage" (12c., Modern French cellier), from Latin cellarium "pantry, storeroom," literally "group of cells;" which is either directly from cella "small room, store-room" (from PIE root *kel-(1) "to cover, conceal, save"), or from noun use of neuter of adjective cellarius "pertaining to a storeroom," from cella. The sense "room under a house or other building, mostly underground and used for storage" gradually emerged in late Middle and early Modern English. Related: Cellarer. Cellar-door attested by 1640s.